1. Field of the Invention
This invention relates to fluid handling processes and apparatus. More particularly, this invention relates to a fluidic oscillator that can control the spraying of high viscosity fluids so that such sprays are uniformly distributed over their target areas.
2. Description of the Related Art
Fluidic oscillators are well known in the prior art for their ability to provide a wide range of liquid spray patterns by cyclically deflecting a liquid jet. The operation of most fluidic oscillators is characterized by the cyclic deflection of a fluid jet without the use of mechanical moving parts. Consequently, an advantage of fluidic oscillators is that they are not subject to the wear and tear which adversely affects the reliability and operation of other spray devices.
Examples of fluidic oscillators may be found in many patents, including U.S. Pat. Nos. 3,185,166 (Horton & Bowles), 3,563,462 (Bauer), 4,052,002 (Stouffer & Bray), 4,151,955 (Stouffer), 4,157,161 (Bauer), 4,231,519 (Stouffer), which was reissued as RE 33,158, U.S. Pat. Nos. 4,508,267 (Stouffer), 5,035,361 (Stouffer), 5,213,269 (Srinath), 5,971,301 (Stouffer), 6,186,409 (Srinath) and 6,253,782 (Raghu).
The nature of the typical oscillations in the flow of a liquid exhausting from such devices into a gaseous environment is shown in FIGS. 1A-1C. The alternating formation of vortices in the top and bottom regions of downstream end of the oscillator's interaction chamber is seen to cause the flow from its outlet to be alternately swept upward or downward such the oscillator's output is spread over a fan angle of approximately 2θ.
This type of oscillating liquid jet can yield a variety of patterns for the downstream distribution of the liquid droplets that are formed as this liquid jet breaks apart in the surrounding gaseous environment. One such possible distribution pattern is shown in FIG. 1C.
For the spraying of high viscosity liquids, the “mushroom oscillator” disclosed in U.S. Pat. No. 6,253,782 and shown in FIG. 2 has been found to be especially useful. However, the flow from such a fluidic oscillator is characterized by having the swept jet, that issues from it, dwell on the end positions of its sweep such that its downstream distribution of droplets, which impact upon a plane that is perpendicular to the direction of the spray, is heavy ended as characterized by a larger volume of the liquid being collected at the two ends of the distribution. See FIG. 3. Considerable difficulties have been encountered in trying to get this type of fluidic oscillator to operate so as to yield more spatially uniform droplet distributions.
Despite much prior art relating to fluidic oscillators, there still exists a need for further technological improvements in this area. For example, there still exist situations in which the known fluidic oscillators are incapable of providing the desired spray patterns under all ranges of operating conditions (e.g., uniform spatial distribution of droplets from high viscosity sprays). Such situations are known to arise in various automotive applications under conditions of extremely cold temperatures.
3. Objects And Advantages
There has been summarized above, rather broadly, the prior art that is related to the present invention in order that the context of the present invention may be better understood and appreciated. In this regard, it is instructive to also consider the objects and advantages of the present invention.
It is an object of the present invention to provide new, improved fluidic oscillators and fluid flow methods that are capable of generating oscillating, fluid jets with spatially uniform droplet distributions over a wide range of operating temperatures.
It is another object of the present invention to provide improved fluidic oscillators and fluid flow methods that are capable of generating oscillating, fluid jets with high viscosity liquids.
It is yet another object of the present invention to provide improved fluidic oscillators and fluid flow methods that yield fluid jets and sprays of droplets having properties that make them more efficient for surface cleaning applications.
These and other objects and advantages of the present invention will become readily apparent as the invention is better understood by reference to the accompanying summary, drawings and the detailed description that follows.